Transcriptional-translational conflict in bladder epithelial homeostasis and cancer

摘要 染色质重塑和蛋白质合成是严格调控的过程，影响基因表达和蛋白质合成。 细胞表型。然而，目前尚不清楚这两种监管机制可能在多大程度上联系在一起或 独立于控制正常的上皮生理和疾病状态。我们发现了一个新的功能 染色质重构体ARID1A与信使核糖核酸翻译延伸的关系此链接涉及 在膀胱癌发生的背景下维持细胞适合性并代表一种新的肿瘤抑制 我们称之为转录-翻译冲突的机制。ARID1A的丢失引发了同时增加的 但也抑制翻译延长因子eEF2，这导致减少 蛋白质合成和预防癌症的发病机制。但是，此过程可以通过恢复 翻译延长，这使得能够有效地合成致癌的mRNA和癌症进展。这 FINDING提供了一个统一的基因表达模型，解释了为什么ARID1A是一种特定于上下文的肿瘤 抑制者。重要的是，ARID1A缺陷肿瘤对药物抑制翻译保持敏感性 伸长起始。最近，我们实验室开发并表征了新的体外和体内模型。 人类和小鼠ARID1A缺陷型膀胱癌，我们也可以切换翻译延长。 我们使用这些模型来发现ARID1A和mRNA翻译过程之间的关键联系 伸长对尿路上皮的动态平衡和膀胱癌的进展至关重要。我们假设 缺乏ARID1A的尿路上皮细胞的转录-翻译冲突是通过减少真核细胞介导的 延伸因子2(EEF2)活性，当逆转时释放稳定的可药物致癌程序 足以推动癌症的发展。我们的长期目标是利用最先进的鼠标模型和 初级器官系统、全转录组多聚体图谱和患者来源的异种移植物 在高度相关的人群中研究ARID1A和蛋白质合成调节之间的基本联系 膀胱癌患者的比例。为此，我们将解决以下目标：1)确定相关性和 尿路上皮细胞转化和癌变中转录-翻译冲突的机制； 阐明基因表达的奇偶性如何使癌症进展，并代表一种特定于背景的治疗方法 脆弱性。这项研究将有助于我们对膀胱癌和膀胱癌的生物学有更深入的了解。 一种治疗致命疾病患者的新范例。我们的工作对我们的进步尤为重要 精确医学，因为它寻求机械地将高度流行的膀胱癌基因(ARID1A)联系在一起 损失)到一种新的治疗方式，为膀胱癌患者带来了治疗希望。

ABSTRACT Chromatin remodeling and protein synthesis are tightly regulated processes that impact gene expression and cellular phenotypes. However, it is unknown to what extent these two regulatory mechanisms may be linked or independent in controlling normal epithelial physiology and disease states. We have uncovered a new functional relationship between the chromatin remodeler ARID1A and mRNA translation elongation. This link is involved in maintaining cellular fitness in the context of bladder carcinogenesis and represents a new tumor suppressive mechanism we call transcriptional-translational conflict. Loss of ARID1A triggers a simultaneous increase in oncogenic transcripts, but also inhibition of the translation elongation factor eEF2, which results in a reduction in protein synthesis and prevents cancer pathogenesis. However, this process can be reversed by restoring translation elongation, which enables the efficient synthesis of oncogenic mRNAs and cancer progression. This finding provides a unified gene expression model which explains why ARID1A is a context specific tumor suppressor. Importantly, ARID1A deficient tumors retain a sensitivity to pharmacologic inhibition of translation elongation initiation. Recently, our laboratory has developed and characterized new in vitro and in vivo models of both human and murine ARID1A deficient bladder cancer where we can also toggle translation elongation. We have used these models to discover a critical link between ARID1A and the process of mRNA translation elongation that is vital for urothelial homeostasis and bladder cancer progression. We hypothesize that transcriptional-translational conflict in urothelium lacking ARID1A is mediated through decreased eukaryotic elongation factor 2 (eEF2) activity, which when reversed unleashes a poised druggable oncogenic program sufficient to drive cancer progression. Our long-term objective is to utilize state-of-the-art mouse models and primary organoid systems, whole transcriptome polysome profiling, and patient derived xenografts to definitively investigate the fundamental link between ARID1A and protein synthesis regulation in a highly relevant population of bladder cancer patients. To do so, we will address the following aims: 1) Determine the relevance and mechanism of transcriptional-translational conflict in urothelial cell transformation and carcinogenesis; and 2) Elucidate how gene expression parity enables cancer progression and represents a context specific therapeutic vulnerability. This research will help us gain a deeper understanding of the biology of bladder cancer and open a new paradigm for treating patients with lethal disease. Our work is particularly important for the progress of precision medicine because it seeks to mechanistically tie a highly prevalent bladder cancer genotype (ARID1A loss) to a new treatment modality that holds therapeutic promise for bladder cancer patients.